Amnesia/Memory Recall of Pre-Trauma Childhood

Hello again, little-details. It's been a while (and a change of name) since I posted here, so hopefully I'm getting this right.

Setting: A mash-up historical period, with some elements from later Medieval and some post-Medieval, vaguely Scandinavian in feel, with magic in existence but very rare (other than the abundant presence of dragons). (For those who know the fandoms, this is an attempt to weave together the films How To Train Your Dragon and Frozen.)

Background on the character (cut for length and potential triggers relating to non-consensual violence and child trauma):

The character has magical powers and was entirely comfortable using them as a child. However, in an accident when she was eight, she almost caused the death of her younger sister. Her parents went to the priesthood of the city for help, and on finding out that the girl had magical powers they ordered her to be banished. (To be precise, her father manages to have her banished rather than killed, and the girl is aware of this.)

She is rescued by one of the people who live in the wild country and are vague enemies of the city, and lives for them with three years, now hiding her magic. During this time, she has to learn a new language (albeit one related to her previous one), as well as a whole set of survival skills. These people actively discourage her from thinking about her past.

At the age of eleven, her powers become stronger and start to lash out without her intending to use them. At this point, she is also ostracised from the semi-sedentary 'village' and forced to live by herself in the wild country. She has the occasional run-ins with people after this time, but most would be hostile to her and there has been at least one occasion where her magic killed one of them who attacked her. While there have been violent incidents, there have been no sexually violent (or any sexual) incidents.

At the age of eighteen, she finally has a good encounter with someone, who helps to set her broken ankle, brings her food and teaches her their language. For a few months, she only interacts with this person, and after that is bought back to his village as a result of serious events. About a year after this, they return to her city of origin, chance to meet her sister, and the backstory comes out.

Now, my actual questions:

1) The character was a princess when she lived in her home city (until the age of eight). What is the chance that she doesn't remember/really understand this by the age of nineteen? She has some memories from before the age of eight, but if I'm researching right they would likely be more episodic and isolated, and if she remembers the events that led to her banishment then they could well be hyper-clear. Is there any way that this could overshadow or even 'force out' most of her other memories of that time?

2) She remembers her sister's name, but is unwilling to talk about it. What is the chance that she does not remember her parents' names (until prompted by her sister)?

3) How likely is it that she will recognise the palace, but not really know that she used to live there? Or if she does remember, is it possible that she doesn't know in what capacity she lived there, such that other people might assume she was a servant?

4) On the other side, her sister was five when they were separated, and has been told for the last eleven years that her sister was kidnapped and believed lost. She has been discouraged from talking about her. When they meet again, what is the chance that the younger sister would recognise the elder? The elder sister has very distinctive white-blonde hair and a very similar facial structure to both the younger sister and their mother. Even if it is a momentary incredulous greeting that the elder sister reacts to (thus confirming her identity), would it be possible that the younger could see this apparent stranger and blurt out her sister's name?

I know that there are broader issues of resocialisation that come into play here, as well as the more general effects of the trauma about what happened, but I think that I've got those. It's this specific set-up that I'm struggling to get quite right.

Research Done:Looked through little_details; this response indicates that a seven year old would not retain much in the way of memory; this post about memories retained by a six-year old remark that it is based on being encouraged to remember;

More generally, I've googled "development of memory", "childhood memory development", "childhood trauma amnesia" and a few variations thereon. This article on amnesia, dissociation and childhood trauma is good for overall trends, but it's not clear whether the amnesia could extent to events outside the trauma. I've tried looking through PubMed, but most of the trauma spoken about is childhood abuse or sexual abuse, and the responses being viewed are more extreme.

I've also done research on feral children (not the same circumstances, but it does help for some of the social aspects), and I know more about PTSD than I would like to from both research and personal experience.